1. Field of the Invention
The present invention relates to fuse blocks generally, and in particular to a switching apparatus for selectively connecting and disconnecting a fuse block from its power source.
2. Discussion of the Related Art
Molded case fuse blocks are well known in the art for protecting electrical circuitry from damage due to power surges and the like. In particular, conventional fuse blocks are typically disposed within a cabinet to protect the associated electric circuitry from the external environment. In order to reduce the possibility of inadvertent contact with the live wiring inside the cabinet, it had become desirable to provide a system for automatically electrically disconnecting the fuse block from power when the cabinet door is opened.
For example, referring to FIG. 1, a cabinet 10 is provided having opposing upper and lower walls 12 and 14, respectively, connecting at their left and right ends to opposing side walls 16. The back end of the cabinet 10 is enclosed by a rear wall 18, and at its front end by a door 20. Door 20 is hingedly connected to one of the side walls 16. A fuse block 22 is mounted to the inner surface of rear wall 18 such that fuses 24 are easily accessible to the user when door 20 is open. A series of electrical input leads 26 connect the fuse block 22 to a remote power source (not shown). A set of electrical output leads 28 extend through the lower wall 14 and connect the fuse block 22 to other circuitry. An operator 30 extends outwardly from fuse block 22 towards door 20, and is rotatable about its axis of extension to electrically connect and disconnect fuses 24 from electrical input leads 26.
Referring now also to FIG. 2, door 20 includes a door knob 32 that is configured to engage the rotatable operator 30. In particular, a pair of cylindrical locking pins 34 extends horizontally outwardly from either side of the outer end 31 of rotatable operator 30. A corresponding keyhole 36 is disposed in door knob 32, and includes a first horizontally extending slot 38 sized to receive locking pins 34. Key hole 36 further includes a second vertically extending slot 40 that intersects with slot 38 and is sized to receive the outer end 31 of rotational operator 30.
During operation, when door 20 is closed, rotatable operator 30 and corresponding locking pins 34 are inserted into keyhole 36 of door knob 32. Door knob 32 is subsequently rotated counterclockwise along the direction of arrow A, which further causes keyhole 36 to correspondingly rotate rotational operator 30 counterclockwise in the direction of arrow B to once again establish electrical connection between fuse block 22 and the power source. As door knob 32 is rotated in the direction of arrow A, a door latch (not shown) locks the door 20 in a closed position. Accordingly, in order to subsequently open the door 20, door knob 32 is rotated clockwise to unlock the door 20 and automatically rotate operator 30 to disconnect the fuse block 22 with the power source.
A user is therefore advantageously unable to access the interior of cabinet 10 without first disconnecting the fuse block 22 from the power source via operator 30. However, this system suffers from drawbacks related to both fabrication and use. For example, the fuse block 22 and door knob 32 must be precisely mounted in their proper location in order to ensure that keyhole 36 is in mating alignment with locking pins 34. This is a difficult and sometimes tedious time consuming process. Additionally, when the door 20 is open, and fuse block 22 is disconnected from the power source, the user has the ability to manually rotate operator 30 in the direction of arrow B to reconnect the fuse block 22 and the power source while cabinet 10 is open.
What is therefore needed is a switching apparatus for a fuse block that avoids the manufacturing difficulties associated with conventional designs, and that limits a user""s ability to inadvertently turn the fuse block on while the cabinet door is open.
In accordance with one aspect of the invention, a switching apparatus is provided for a fuse block that is disposed in a cabinet. The fuse block is of the type having at least one fuse operable to conduct current from a power source to a load and rotatable operator extending along an axis is operable to rotate about the axis between a closed and open position to correspondingly electrically connect and disconnect the fuse block with respect to the power source. The switching apparatus includes a handle mechanism that is mountable to a cabinet surface and movable between a first position and a second position. An actuating mechanism is provided having (A) a stationary member fixed relative to the fuse block; (B) a movable member movably connected to the stationary member; and (C) a linkage linked to the movable member and connected to the rotatable operator for rotating the rotatable operator in response to movement of the movable member. A cable assembly is attached to the handle at a first end and attached to the actuating mechanism at a second end opposite the first end. Movement of the handle mechanism from the first position to the second position causes the cable to translate the movable member with respect to the fuse block, thereby rotating the linkage and rotatable operator to electrically disconnect the fuse block from the power source.